This invention relates to a system for driving a plurality of slit strip rewinding shafts or cores. In particular, this invention relates to a method and apparatus for driving a plurality of independently driven rewind shafts or cores for simultaneously rewinding a plurality of slit strips.
In a web slitting machine, a flexible web material is slit into a plurality of narrower continuous strips of a uniform or different widths in a slitting section. These slit strips are simultaneously rewound into a plurality of rolls. The slit web strips are seemingly uniform in thickness but actually and precisely they are not uniform in thickness. Firstly, the thickness differs from strip to strip and, secondly, the thickness of each strip varies along its entire length. Although the difference or variation of the web thickness is rather small, it causes a corresponding difference in the diameter of strip rolls being wound on the rewind shaft. In winding simultaneously a plurality of slit strips, any difference in diameter among strip rolls being wound must be accommodated in order to rewind slit strips into rolls of a substantially uniform density or hardness. One prior and typical approach to accommodate a difference of roll diameter is to provide a separate rewind shaft for each strip roll to be wound and to have an independent driving source for each rewind shaft. The independent drive approach is generally satisfactory and acceptable when simultaneously rewinding a plurality of slit strips of a uniform width since it is not difficult and expensive to control the independent driving sources for the rewind shafts. However, when simultaneously rewinding a plurality of slit strips of different widths, it is necessary to separately control the independent driving sources for the rewind shafts, which involves an extremely complicated and expensive control system and procedure.